Culturable fungal diversity of shrimp Litopenaeus vannamei boone from breeding farms in Brazil

Litopenaeus vannamei, which is the most common shrimp species cultivated in the northeast of Brazil, is very susceptible to microbial diseases, and this consequently affects productivity. There are reports of bacteria, viruses and protozoa in these shrimp, but not fungi. This study aims to isolate and identify fungi present in shrimp Litopenaeus vannamei, and in their nursery waters, at two breeding farms in Brazil. The pathogenic potential of the isolates was assessed through the qualitative detection of proteases and aflatoxin B production. The 146 isolated fungi comprised 46 species. Aspergillus, Penicillium and Furarium were the three most relevant genera and Aspergillus flavus was the predominant species with a total of 33 isolates. Most of the isolated species are known as potentially pathogenic to humans and other animals. Eighteen isolates of A. flavus and two of A. parasiticus were able to produce aflatoxin B and 33 out of the 46 species produced protease, indicating that these fungi may also become pathogenic to shrimp and their consumers.

Identification and characterization of filamentous fungi isolated from the sunflower (Helianthus annus L.) rhizosphere according to their capacity to hydrolyse inulin

Filamentous fungi able to hydrolyse inulin have been isolated from the rhizosphere of plants whose roots contain this polysaccharide. This study reports results concerning the isolation and identification of filamentous fungi from the soil used for sunflower cultivation and from the sunflower rhizosphere cultivated in field and in greenhouse. Fungi were evaluated according to their capacity to hydrolyse inulin and the variation in the diversity of these fungi during the plant's life cycle was also accessed. Forty-nine species of filamentous fungi were isolated. Penicillium and Aspergillus were the genera that presented higher number of species, nine and seven, respectively. At the end of the sunflower life cycle, cultivated both in field and in the greenhouse, a lower numbers of species were isolated. One hundred and fifty nine strains of filamentous fungi were isolated from soil and from the sunflower rhizosphere; from these, 79 (49.7%) were able to hydrolyse inulin. There was not significant difference in the proportion of species able to hydrolyse this polysaccharide during the sunflower's life cycle, in plants cultivated in field or in greenhouse. Although the sunflower's rhizosphere is a source of filamentous fungi able to hydrolyse inulin, that might be used in biotechnological processes. This system does not present a higher density of such microorganisms. Species of Aspergillus, Chaetomium, Cunninghamella, Emericela, Eupenicillium, Fusarium, Myrothecium, Neosartorya, Neocosmospora, Penicillium and Thielavia are being related by first time as inulinase producers.

Fungos filamentosos capazes de hidrolisar inulina tem sido isolados de rizosfera de plantas que acumulam esse polissacarídeo nas raízes. Este estudo compreendeu o isolamento e identificação de fungos filamentosos do solo utilizado para o cultivo do girassol e da rizosfera de girassol cultivado em campo e em casa de vegetação, a fim de verificar se há variação na diversidade destes fungos ao longo do ciclo de vida da planta. O fungos foram também caracterizados quanto a capacidade de hidrolisar inulina. Das quarenta e nove espécies de fungos filamentosos isoladas, Penicillium e Aspergillus foram os gêneros que apresentaram maior número de espécies, nove e sete, respectivamente. No final do ciclo de vida do girassol, cultivado tanto em campo quanto em casa de vegetação, foi isolado um menor número de espécies. Cento e cinquenta e nove amostras de fungos filamentosos, isoladas do solo e da rizosfera de girassol e destas 79 (49,7%) foram capazes de hidrolisar inulina. Não houve diferença significativa quanto a proporção de espécies capazes ou não de hidrolisar esse polissacarídeo, ao longo do ciclo de vida do girassol, cultivado tanto em campo quanto em casa de vegetação. Embora a rizosfera de girassol seja uma fonte de fungos filamentosos capazes de hidrolisar inulina, que podem ser utilizados em processos biotecnológicos, ela não atua de modo a concentrar fungos com esta característica. Espécies de Aspergillus, Chaetomium, Cunninghamella, Emericela, Eupenicillium, Fusarium, Myrothecium, Neosartorya, Neocosmospora, Penicillium and Thielavia estão sendo relatados pela primeira vez como produtores de inulinase.